The present invention relates to a small-size jack.
As electronic devices are becoming smaller in size, there have been growing demands for smaller-size electronic parts and components. One example of such an electronic component is a jack, which has a contact member that will be of poor durability if the size of the jack is reduced. More specifically, a smaller-size jack has a reduced depth which requires a shorter contact member for contact with a plug inserted in the jack. When the plug is inserted in the jack, the end of the contact member is resiliently bent by the plug. As the plug is repeatedly inserted and pulled out, the short contact member is repeatedly bent and undergoes localized deformation. The contact member will then be liable to be broken off relatively easily, and therefore has a relatively short service life.
One solution to the above problem is to reduce the thickness of the contact member thereby to enlarge the area thereof which will be deformed by the inserted plug. Stated othewise, the reduced thickness of the contact member allows the latter to flex bodily for increased durability of the contact member. However, the thin contact member exhibits less resilient force and suffers from the problem of a reduced pressure of contact with the plug. When the contact member and the plug are brought into contact with each other under reduced pressure, no good electric contact is achieved between the contact member and the plug. Another problem with the less resilient contact member is that the plug cannot be retained in the jack with a sufficient retentive force, and will easily be pulled out when the cord connected to the plug is subjected to small tension. In addition, when the plug is inserted in the jack, the user fails to get a tactile assurance that the plug is properly inserted in the jack.
To avoid the above drawbacks, there have been proposed a jack including a coil spring interposed between the movable end of a contact member and a body, as disclosed in U.S. Pat. No. 3,536,870 issued on Oct. 27, 1970 and Japanese Laid-Open Utility Model Publication No. 52-95085. Use of such a coil spring however results in an increased number of parts making up the jack. The disclosed jack is subjected to limitations on smaller designs since it is awkward to assemble the contact member and the coil spring in a required interrelationship into the small body.
The conventional small-size jacks have also been disadvantageous in that a plug tends to be inserted into and pulled out of the jack obliquely to a normal position, with the result that the contact member will be subjected to excessive bending by the plug resulting in permanent deformation and the jack will become defective. To cope with this shortcoming, Japanese Laid-Open Utility Model Publication No. 53-24891 and Japanese Utility Model Publication No. 56-39185 disclose a jack including a body having an integral projection that serves as a stop for receiving a contact member at a suitable angle. More specifically, when a movable portion of the contact member is displaced to a certain extent by a plug inserted into the jack, the back of the contact member which is opposite to the surface held against the plug is brought into abutment against the projection, so that the movable portion of the contact member will not be displaced farther. The projection however serves only to prevent the permanent deformation of the contact member, and is not effective in strengthening the resiliency of the contact member. The proposed jack thus includes a coil spring for assisting the contact member in becoming satisfactorily resilient, as shown in the aforementioned Publication No. 53-24891.